Diagnostic Utility of Nocturnal Hypoxemia Measures in Severe Obstructive Sleep Apnea: A Retrospective Analysis

Background and Objective Despite its frequency, obstructive sleep apnea (OSA) is still underdiagnosed. Apnea-Hypopnea Index (AHI) has traditionally been used as a reference for diagnosing OSA. The gravity of cardiovascular diseases associated with OSA is the main reason to encourage scientists to search for new markers.Methods A retrospective and analytic study in the department of pneumology D of Abderahmen Memi Ariana from 2014 to 2024 with a total of 770 patients. The severity of OSA was categorized using the AHI: AHI of 30 or more occurrences per hour is considered severe OSA; AHI of 5 to less than 30 events per hour is considered non-severe OSA, which is further classified as moderate OSA and mild OSA.Results A total of 401 patients had severe OSA (52.07%), with a higher age (58.65 vs. 56.96 years for moderate OSA and 54.18 years old for mild OSA, p=0.001) and a higher body mass index with a significant difference (37.50 vs. 36.22 kg/m<sup>2</sup> for moderate and 35.18 kg/m<sup>2</sup> for mild OSA, p=0.001). The oxygen desaturation index (ODI) in the severe OSA group was noticeably higher and nearly triple the ODI of the non-severe OSA group. Patients with severe OSA had a significantly different mean oxygen saturation (91.93% vs. 93.34%, p=0.01). Investigated markers were considered effective screening tests for severe OSA, with an area under the receiver operating characteristic curve greater than 0.70.Conclusions While AHI remains the standard for OSA diagnosis and staging, emerging evidence highlights its limitations as a sole criterion. In our cohort, nocturnal hypoxemia measures were reliable markers of severe OSA and may better identify patients at high cardiovascular risk. Our findings support incorporating nocturnal hypoxemia measures into OSA assessments along with AHI.